1. Field of the Invention
The present invention relates to a device for sensing an electric current by measuring an intensity in magnetic field around an ultrasonic fiber constructed in the device.
2.Description of the Prior Art
Conventional devices for measuring magnetic field intensity include a semiconductor-type device, which makes use of the Hall effect or magnet resistance effect in a semiconductor. The semiconductor-type device is of practical use, however, has a problem that a dynamic range for measurement is limited. Recently, a device using an optical-fiber cable is proposed for measuring magnetic field intensity caused by an electric current flowing in an electric wire. The optical-fiber type of device makes use of a delay-time change accompanying with an intensity change in magnetic field, and has a problem of the difficulty in substantially shortening the optical-fiber cable.